The present invention relates to an apparatus and associated method for testing an object using radial acceleration, and more particularly to an apparatus and method for testing tire-mounted units, such as tire pressure monitoring units.
Tire pressure monitoring systems are known in the art. Some examples of tire pressure monitoring systems are disclosed in U.S. Pat. No. 5,285,189 and U.S. Pat. No. 5,844,131.
A tire pressure monitoring system senses inflation pressure within a vehicle tire. The sensory information sensed by the monitoring system is typically displayed to the vehicle operator in some fashion, such as via a digital readout on the vehicle dashboard. To sense the inflation pressure within a tire, typically a portion of the tire pressure monitoring system, such as a monitoring unit, is located in or on the tire. As such, this unit is subjected to rotational force as the tire is rotated. Accordingly, this unit needs to be operable under rotational forces. Devices have been developed to test the operativeness of instruments which are rotated. For instance, U.S. Pat. No. 2,814,944, discloses a centrifugal testing apparatus for subjecting instruments to centrifugal force and to simulate constant or steady state acceleration for test purposes.
The monitoring unit also monitors tire pressure under various operating conditions. For instance, the monitoring unit may monitor the pressure within a tire when the vehicle is driven at various speeds and/or on various road conditions. Additionally, the monitoring unit may monitor the pressure within a tire at different temperatures and surrounding atmospheric pressures. As such, a tire pressure monitoring unit needs to be operable to monitor the pressure within a tire under different operating conditions.
To test the operativeness of a tire pressure monitoring unit under various operating conditions, the vehicle within which the entire monitoring system is integrated can be operated under those conditions. For instance, to test the operativeness of a tire pressure monitoring system at a low atmospheric temperature and a low atmospheric pressure, the vehicle equipped with the monitoring system can be driven in a cold, elevated geographic area, such as on a mountain top. Likewise, to test the operativeness of a tire pressure monitoring system at 150 miles per hour, the vehicle equipped with the monitor can be driven at 150 miles per hour.
For obvious reasons that include, among other things, cost and safety, it is apparent that it would be desirable to be able to test the operativeness of a tire pressure monitoring unit under a variety of operating conditions without having to actually-operate a vehicle under those conditions. Thus, a device that would permit a tire pressure monitoring unit to be tested under a wide variety of operating conditions representative of the conditions under which a vehicle may actually be driven would be desirable.
The present invention is directed to an apparatus and an associated method for testing units that are to be subjected to rotational force. The units may include automotive tire-mounted units, such as a tire pressure monitoring unit.
According to one aspect of the invention, a testing apparatus includes a rotational drive motor, a rotating member, and a drive interconnection operatively connected between the drive motor and the rotating member. The drive interconnection includes a first constant velocity joint, a longitudinal spline interconnection, and a second constant velocity joint. The apparatus also includes a stationary motor mount fixed to the drive motor, a test unit holder located on the rotating member, and a three-dimensional motion drive operatively connected to the rotating member.
According to another aspect of the invention, a method for testing automotive tire-mounted units includes the steps of locating a test unit on a member, holding the test unit on the member, operatively connecting a drive motor to the member, starting the drive motor, rotating the member with the drive motor, and moving the test unit in three dimensional space without affecting the drive motor.